Liquid crystal display device

ABSTRACT

In order to prevent irreversible deformation of column-shaped spacers which retain the gap between a pair of substrates between which the liquid crystal layer of a liquid crystal display device is interposed, spacers which assist in preventing such irreversible deformation are newly provided. According to the invention, two or more kinds of spacers which differ in height from a reference surface are disposed on one of the pair of substrates. In addition, a step pattern with which the spacers are to come into contact is formed in advance on the other of the pair of substrates so that the heights of the spacers can be made different.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation application of U.S. application Ser.No. 10/004,805 filed Dec. 7, 2001, now U.S. Pat. No. 7,133,108. Priorityis claimed based on U.S. application Ser. No. 10/004,805 filed Dec. 7,2001, which claims the priority of Japanese Patent Application No.2000-379773 filed on Dec. 8, 2000, all of which is incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device and,more particularly, to a liquid crystal display device in which a pair ofsubstrates are opposed to each other with a predetermined gap interposedtherebetween by spacer materials and a liquid crystal compound isretained in the gap.

2. Description of the Related Art

In recent years, liquid crystal display devices are widely used assmall-sized display devices and display terminals for so-called OAequipment. These kinds of liquid crystal display devices basicallyinclude a so-called liquid crystal panel (also called a liquid crystalcell) in which a layer of a liquid crystal compound (or a liquid crystallayer) is interposed between a pair of substrates at least one of whichis made of a transparent glass plate, a plastic substrate or the like.Such a liquid crystal panel is generally classified into a type (simplematrix) which selectively applies voltages to various kinds ofpixel-forming electrodes formed on the substrates of the liquid crystalpanel to change the alignment direction of liquid crystal moleculeswhich constitute a liquid crystal compound of a predetermined pixelportion, thereby forming pixels, and a type (active matrix) in whichvarious kinds of electrodes and pixel-selecting active elements areformed on the substrates of the liquid crystal panel so that selectionis made from these active elements to change the alignment direction ofthe liquid crystal molecules of pixels lying between pixel electrodesand reference electrodes connected to the active elements, therebyforming the pixels.

In general, the active matrix type liquid crystal display device adoptsa so-called vertical electric field mode in which an electric field forchanging the alignment direction of its liquid crystal layer is appliedacross an electrode formed on one of its substrates and an electrodeformed on the other.

On the other hand, a liquid crystal display device of so-calledin-plane-switching mode (abbreviated to IPS mode) in which the directionof an electric field applied to its liquid crystal layer is madeparallel to its surface surfaces has been put to practical use. As adisclosed example of this in-plane-switching mode of liquid crystaldisplay device, a liquid crystal display device constructed to obtain avery wide viewing angle by using comb-teeth electrodes on one of twosubstrates has been known (Japanese Patent Publication No. 21907/1988and U.S. Pat. No. 4,345,249).

A liquid crystal panel for use in this kind of liquid crystal displaydevice is constructed so that spacers are interposed in the gap betweena pair of insulating substrates in which a liquid crystal compound issealed, in order to hold the gap at a predetermined value.

In general, related-art spacers employ spherical spacers made of amaterial which contains resin or glass, or spherical spacers made of asimilar material and subjected to surface treatment with a coloringagent, an adhesive or an alignment treatment agent, and such spacers arescattered between the electrode-side inner surfaces of the insulatingsubstrates by a static electricity dispersion method, a semi-dry spraymethod or the like.

In addition, it has also been proposed that instead of such sphericalspacers, a predetermined pattern of column-shaped spacers (projections)is formed by a photolithographic technique, a printing technique or thelike on at least a part of an area (non-pixel part) shielded from lightby a light shield part (a light shield film or a black mask) (JapanesePatent Laid-Open Nos. 325298/1995 and 286194/1996).

SUMMARY OF THE INVENTION

In the aforementioned related art of forming column-shaped spacers on asubstrate, one spacer is formed for each pixel. Each of the spacers issecured to one of opposed substrates, and a predetermined area of eachof the spacers is in contact with the other. The inventors of thepresent application, however, have found out the problem that if amultiplicity of spacers are provided, the contact area of spacersbecomes wide and frictional force increases. Specifically, if a force isapplied from the outside to two opposed substrates of a liquid crystalpanel so that their surfaces deviate from each other in parallel, aslight deviation temporarily occurs between the mutually opposedsubstrates owing to an external force parallel to the substratesurfaces, but if the number (contact area) of spacers is large, thedeviation is not restored due to the friction between the spacers andthe substrates even after the substrates have been released from theexternal force.

To solve the above-described problem, it may be considered that thenumber of spacers is decreased to narrow the contact area. However, ifthe number of spacers is decreased, another problem occurs.Specifically, when a temporary load is applied from the outside in adirection perpendicular to the substrate surfaces, the limited number ofspacers will undergo elastic deformation and the gap between thesubstrates will become irreversibly locally small resulting in poordisplay.

Therefore, the present inventors provide a liquid crystal display devicein which spacers which, when a temporarily large load is applied fromthe outside, function to dispersively bear the load are disposed inaddition to spacers which function to retain the gap between itssubstrates.

Several examples of the liquid crystal display device according to theinvention will be described below.

A first example of the liquid crystal display device includes a firstsubstrate, a second substrate provided in opposition to the firstsubstrate, a liquid crystal layer provided between the first substrateand the second substrate, and spacers provided on the first substrate,and the liquid crystal layer is provided between the spacers and thesecond substrate. In other words, at least one of plural spacers formedon a liquid-crystal-layer-side main surface of the first substrate isnot brought into contact with a liquid-crystal-layer-side main surfaceof the second substrate opposed to the first substrate or stacked matter(such as an alignment film, a protective film and video signal lines)provided on the liquid-crystal-layer-side main surface of the secondsubstrate. Accordingly, the liquid crystal compound (liquid crystallayer) is interposed between the at least one spacer and theliquid-crystal-layer-side main surface of the second substrate or thestacked matter provided thereon. In a case where a conductive layer madeof an alignment film, a protective film, a conductive oxide or the likeis formed on the surface of the at least one spacer, the top surface ofsuch film or layer (if plural films and layers are stacked on thesurfaces of the spacers, the uppermost surface of this stackedstructure) is spaced apart from the liquid-crystal-layer-side mainsurface of the second substrate or the stacked matter provided thereon.

A second example of the liquid crystal display device includes a TFTsubstrate (having a main surface provided with plural pixel areas eachhaving at least a pixel electrode and a switching element connectedthereto), a color filter substrate having a main surface on which pluralcolumn-shaped spacers are provided (a main surface on which pluralprojections which become spacers are formed), and a liquid crystal layerprovided between the main surface of the TFT substrate and the mainsurface of the color filter substrate (a liquid crystal compound sealedin the space between the main surfaces of both substrates). Therespective column-shaped spacers have depressed surfaces on theirsurfaces (their top surfaces as viewed from the main surface of thecolor filter substrate) to be brought into contact with the TFTsubstrate, and when a force is applied between the TFT substrate and thecolor filter substrate, at least one of the plural column-shaped spacersis deformed and the depressed surface provided on the top surface of theat least one spacer is also brought into contact with the TFT substrate.The top surface of the at least one column-shaped spacer may be broughtinto contact with the liquid-crystal-layer-side main surface of the TFTsubstrate, but also a structure such as a protective film and analignment film formed on the liquid-crystal-layer-side main surface ofthe TFT substrate. Switching elements provided on the TFT substrate maybe not only so-called field effect thin film transistors but diodes(thin film diodes, TFDs).

A third example of the liquid crystal display device includes a TFTsubstrate (having a main surface provided with pixel areas each havingat least a pixel electrode and a switching element connected thereto), acolor filter substrate, and column-shaped spacers which retain the gapbetween the TFT substrate and the color filter substrate (form a spacebetween the main surfaces of both substrates). The respectivecolumn-shaped spacers have contact surfaces which are disposed incontact with a substrate (e.g. one of the TFT substrate and the colorfilter substrate) and are respectively placed at boundary positions ofsteps provided on the substrate, and the respective contact surfaces ofthe column-shaped spacers are disposed in contact with the steps attop-side portions thereof (for example, projecting portions as viewedfrom the liquid crystal layer) during the state of retaining an ordinarygap between both substrates, but when an external force is temporarilyapplied, the column-shaped spacers are elastically deformed and are alsobrought into contact with bottom-side portions of the respective steps(for example, depressed portions as viewed from the liquid crystallayer).

A fourth example of the liquid crystal display device includes a pair ofsubstrates (e.g. a TFT substrate and a color filter substrate), andcolumn-shaped spacers for retaining the gap between both substrates arerespectively disposed on the top sides of steps provided within eitherof the main surfaces of the pair of substrates, while reinforcingspacers for resisting a temporarily applied external force are providedbelow the steps.

A fifth example of the liquid crystal display device includes a TFTsubstrate, a color filter substrate, and column-shaped spacers providedbetween both substrates. The column-shaped spacers are respectivelydisposed on steps provided on the color filter substrate, and the stepsare formed in the step of forming a light shield film pattern or a colorfilter pattern on the color filter substrate, or in the similar step tothis.

These and other objects, features and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic cross-sectional view showing a spacer of a liquidcrystal display device according to one embodiment of the invention, andFIG. 1B is its plan view seen from the top side of a substrate;

FIG. 2 is a schematic plan view showing the pixel construction of theliquid crystal display device according to the embodiment of theinvention;

FIG. 3 is a schematic cross-sectional view showing the spacer of theliquid crystal display device according to the embodiment of theinvention;

FIG. 4 is a schematic view aiding in describing a rubbing method for theembodiment of the invention;

FIG. 5 is a schematic cross-sectional view showing a spacer of theliquid crystal display device according to the embodiment of theinvention;

FIGS. 6A and 6B are schematic cross-sectional views showing spacers ofthe liquid crystal display device according to the embodiment of theinvention;

FIG. 7 is a schematic plan view showing another pixel structure of theliquid crystal display device according to the embodiment of theinvention;

FIG. 8 is a schematic cross-sectional view showing spacers of the liquidcrystal display device according to the embodiment of the invention;

FIGS. 9A to 9D are a schematic process diagram showing the process offorming a base portion on which to provide a spacer of the liquidcrystal display device according to the embodiment of the invention;

FIGS. 10A to 10C are a schematic process diagram showing the process offorming a spacer of the liquid crystal display device according to theembodiment of the invention;

FIGS. 11A to 11C are a schematic process diagram showing the process offorming a spacer of the liquid crystal display device according to theembodiment of the invention;

FIG. 12 is a schematic plan view showing the construction of a pixelstructure of the liquid crystal display device according to theembodiment of the invention;

FIG. 13 is a schematic plan view showing a spacer of the liquid crystaldisplay device according to the embodiment of the invention;

FIG. 14 is a schematic plan view of a color filter substrate, showing aposition at which to provide a spacer of the liquid crystal displaydevice according to the embodiment of the invention;

FIG. 15 is a schematic circuit diagram showing the circuit of the liquidcrystal display device according to the embodiment of the invention; and

FIG. 16 is a schematic construction diagram showing the construction ofconstituent parts of the liquid crystal display device according to theembodiment of the invention.

DETAILED DESCRIPTION

A preferred embodiment of the invention will be described below indetail with reference to the accompanying drawings.

FIGS. 1A and 1B are schematic views showing part of a color filtersubstrate, aiding in explaining one embodiment of the liquid crystaldisplay device according to the invention. FIG. 1A is a cross-sectionaltaken along line I-I of FIG. 1B. FIG. 1B is a plan view seen from thetop side of FIG. 1A.

In FIGS. 1A and 1B, reference numeral 1 denotes a spacer, referencenumeral 2 denotes a color filter, reference numeral 3 denotes a blackmask, reference numeral 4 denotes a protective film (not shown in FIG.1B), reference numeral 5 denotes a transparent substrate, and referencenumeral 6 denotes a depression provided on the top surface of the spacer1. The depression 6 will be described later in detail.

As shown in FIGS. 1A and 1B, the black mask 3 is formed on thetransparent substrate 5. The black mask 3 is made of a film of blackresin or metal, and has the function of blocking light. The color filter2 is provided in each aperture of the black mask 3. The color filter 2is made of a resin colored with a pigment or a dyestuff, and passeslight of particular wavelength.

The protective film 4 is formed to cover the color filter 2 and theblack mask 3. The protective film 4 is also called an overcoat film, andserves to protect a surface of the color filter 2 and the black mask 3and also to protect a liquid crystal compound from contamination bycolor filter components. An end portion 2B of the color filter 2overlaps the black mask 3 and there is a difference in film thicknessbetween the color filter 2 and the black mask 3, so that a step occursat the end portion 2B of the color filter 2. The protective film 4 alsohas the effect of burying and leveling the step formed by the colorfilter 2 and the black mask 3, by covering the color filter 2 and theblack mask 3.

The spacer 1 is formed on the protective film 4. The spacer 1 serves toretain a constant gap between the color filter substrate and a TFTsubstrate (not shown) which is provided in opposition to the colorfilter substrate as will be described later, and the liquid crystalcompound is retained in the gap formed by the spacer 1. As shown in theschematic plan view of FIG. 1, the position where the spacer 1 is formedlies over the black mask 3. Since the spacer 1 is hidden by the blackmask 3, the spacer 1 does not stand out when the liquid crystal displaydevice is displaying an image. Incidentally, although FIGS. 1A and 1Bshow only one spacer 1 on the transparent substrate 5, multiple spacers1 are formed in matrix form on the entire surface of the transparentsubstrate 5 (also called the color filter substrate) to retain theconstant gap between the top surface of the transparent substrate 5 andanother substrate (for example, the TFT substrate) opposed to the topsurface.

After the spacer 1 has been formed over the transparent substrate 5, analignment film (not shown) is formed, and the alignment treatment ofrubbing the alignment film with cloth or the like is applied to thealignment film. In this alignment treatment, there occurs the problemthat uniform rubbing cannot be effected owing to the protrusion of thespacer 1. To cope with this problem, the spacer 1 is formed at such aposition that the portion of the alignment film that is formed over thespacer 1 and may be nonuniformly rubbed during the rubbing treatment ofthe alignment film is hidden as entirely as possible by the black mask3.

As described previously, the spacer 1 has the role of keeping constantthe gap in which the liquid crystal compound is retained (for example,the thickness of a space which separates the main surface of the colorfilter substrate and the main surface of the TFT substrate opposedthereto), and it is, therefore, necessary to set the height of thespacer 1 with high accuracy. If the heights of the spacers 1 are notconstant, unevenness will occur in the thickness of a liquid crystallayer (the layer of the liquid crystal compound sealed in the spacebetween the substrates). If unevenness occurs in the thickness of theliquid crystal layer, there occurs a problem such as a decrease indisplay quality due to the occurrence of unevenness in the optical pathlength of light which passes through the liquid crystal layer. For thisreason, during the formation of a layer which becomes the material ofthe spacer 1, it is necessary to form the layer to a uniform thickness.

As described above, to form such spacers 1, it is necessary to formmultiple spacers at particular positions while controlling therespective heights of the multiple spacers with high accuracy. To thisend, a method is used in which a layer which becomes the material of thespacers 1 is formed to a uniform thickness and is patterned into aparticular shape.

A resin material is used as the material of the spacer 1. As the resinmaterial, it is possible to use, for example, a photosensitive acrylicresin varnish “OPTMER NN500” (OPTMER.RTM .: trade name) which is anegative type resist made by JSR Corporation. The resist material isapplied by spin coating or the like to the transparent substrate 5 onwhich the black mask 3, the color filter 2 and the protective film 4 areformed, and the resist is exposed to the pattern of the spacer 1 byusing a mask. After that, the resist is developed with a remover and iscured by heating, thereby forming the spacer 1.

During the formation of the spacer 1, the depression 6 is provided onthe top surface of the spacer 1 by appropriately adjusting thephotosensitive characteristics of the resist material as well as thecharacteristics of curing shrinkage of the resist material during heatcuring. In this embodiment, because the negative type of resist materialis used, a portion having a large amount of exposure is difficult todevelop and remove with the remover, whereas a portion having a smallamount of exposure is easy to remove. For this reason, by producing adifference in the amount of exposure within each aperture of aphotomask, it is possible to form a portion easy to remove and a portiondifficult to remove, on the top surface of the spacer 1. In thisembodiment, the amount of exposure is made smaller in the centralportion of the top surface of the spacer 1 than in the peripheralportion thereof. In one example of such exposure, an opaque film isformed on a transparent substrate member such as a glass substrate, anda photomask is formed by providing apertures (a pattern made oftransparent portions) in part of the opaque film. Through thisphotomask, the opaque film is left to a slight extent, or a mesh- orfringe-shaped opaque pattern is formed, in the central portion of eachof the apertures (in the central area of each of the apertures that isspaced part from the periphery thereof), whereby the quantity of lightpassing through the central portion of each of the apertures is madesmaller than the quantity of light passing through the periphery of eachof the apertures. Not merely in this example, a light quantity to beirradiated onto the top surface of each spacer is made smaller in thecentral portion thereof than in the peripheral portion thereof, therebymaking slightly incomplete the exposure of a photoresist whichconstitutes the central portion of the top surface of each spacer. Inthis manner, the central portion of the top surface of the spacer 1becomes easier to remove with a remover than does the peripheral portionof the same, whereby the depression 6 is formed.

Since the depression 6 is provided on the top surface of the spacer 1,the highest and neighboring portions of the top surface of the spacer 1is brought into contact with the opposite TFT substrate to retain thegap between the transparent substrate 5 and the TFT substrate, whilewhen a large load is applied to a liquid crystal panel, the lowest andneighboring areas of the depression 6 are brought into contact with theTFT substrate and dispersively bear the large load. In this case,regarding the area of the top surface that is brought into contact withthe opposite TFT substrate, the depressed area of the top surface (thearea of a non-contact portion of the top surface) needs to be largerthan the depressed area of the same (the area of a contact portion ofthe same). The required magnitude of a step size (the depth of thedepression 6) needs to be larger than or equal to the amount by whichthe spacer 1 is to be pressed during the assembly of the liquid crystalpanel, and the step size is ordinarily approximately +0.2 μm to +0.3 μm.

A pixel area will be described below prior to the description of aposition at which to dispose each of the spacers 1 within the liquidcrystal panel.

FIG. 2 is a view showing the construction of one pixel area of theliquid crystal display device according to the invention, and is a planview showing the liquid-crystal-side surface of the substrate (in thisembodiment, the so-called TFT substrate) that is disposed in oppositionto the color filter substrate with the liquid crystal interposedtherebetween. The construction of the pixel area shown in FIG. 2 is aso-called in-plane-switching type of pixel construction in which thedirection of electric fields to be applied to a liquid crystal layer ismade approximately parallel to the surfaces of substrates. The liquidcrystal display device of this embodiment is constructed to use a liquidcrystal having positive dielectric anisotropy.

FIG. 2 shows one pixel for the sake of simplicity of illustration, butwithin the liquid crystal panel, individual pixels are disposed inmatrix form to constitute a display part. For this reason, adjacentpixels exist, respectively, on the right, left, top and bottom side ofthe one pixel shown in FIG. 2, and the construction of each of theadjacent pixels is the same as that of the one pixel shown in FIG. 2.

In FIG. 2, reference numeral 100A denotes a TFT substrate, and gatesignal lines 102 which are extended in the horizontal (x) direction andare juxtaposed in the y direction are formed on the surface of the TFTsubstrate 100A. These gate signal lines 102 are made of a material suchas chromium (Cr).

Each adjacent one of the gate signal lines 102, together with eachadjacent one of drain signal lines 103 to be described later (which areextended in the vertical (y) direction and are juxtaposed in thehorizontal (x) direction in FIG. 2), is formed to surround a rectangulararea, and the rectangular area constitutes one pixel area.

A counter voltage signal line 104 which is extended in the horizontal(x) direction in FIG. 2 through approximately the center of the pixelarea is formed of, for example, the same material as the gate signalline 102.

A counter electrode 104A is formed integrally with the counter voltagesignal line 104, and the counter electrode 104A, together with thecounter voltage signal line 104, is formed in an approximately“H”-shaped pattern within the pixel area.

A signal which serves as a reference for a video signal to be suppliedto a pixel electrode 109 which will be described later is supplied tothe counter electrode 104A via the counter voltage signal line 104 sothat electric fields corresponding to the video signal are generatedbetween the pixel electrode 109 and the counter electrode 104A.

Such electric fields have components parallel to the surface of the TFTsubstrate 100A, and the optical transmissivity of the liquid crystal iscontrolled by an electric field made of these components.

Incidentally, a reference signal is supplied to the counter voltagesignal line 104 from the outside of the display part.

An insulating film 105 (refer to FIG. 3) which is made of, for example,a silicon nitride film SIN is formed on the entire surface of the TFTsubstrate 100A on which the gate signal line 102 and the counter voltagesignal line 104 are formed in the above-described manner.

This insulating film 105 has the function of an interlayer insulatingfilm between the gate signal lines 102 and the drain signal lines 103which will be described later, the function of gate insulating films forthin film transistors R TFT (which will be described later) in areas inwhich the respective thin film transistors TFT are formed, and thefunction of dielectric films for additional capacitances Cadd (whichwill be described later) in areas in which the respective addedcapacitances Cadd are formed.

Each thin film transistor TFT is formed to be superposed on the gatesignal line 102 at the bottom left of the pixel area as viewed in FIG.2, and in this area, a semiconductor layer 106 which is formed of, forexample, a-Si (amorphous silicon) is formed on the insulating film 105.

A drain electrode 103A and a source electrode 109A are formed on thesurface of the semiconductor layer 106, thereby forming a thin filmtransistor having a reversed-staggered structure which has a gateelectrode made of a part of the gate signal line 102 and a gateinsulating film made of a part of the insulating film 105.

The drain electrode 103A and the source electrode 109A which overlie thesemiconductor layer 106 are formed at the same time as the pixelelectrode 109 during the formation of, for example, the drain signalline 103.

The pixel electrode 109 is formed to be extended in the y direction asviewed in FIG. 2 in such a manner as to run through the area between theabove-described counter electrodes 104A. In other words, the counterelectrodes 104A are disposed on the opposite sides of each of the pixelelectrodes 109 in such a manner as to be approximately equally spacedapart from each other in each of the pixel areas, whereby electricfields are generated between the pixel electrode 109 and the counterelectrodes 104A.

As is apparent from FIG. 2, the pixel electrode 109 is constructed in,for example, a wedge-shaped pattern which is bent on the counter voltagesignal line 104. Each of the counter electrodes 104A opposed to thepixel electrode 109 is constructed to have a width varied so that eachof the counter electrodes 104A extends in parallel with the pixelelectrode 109.

Specifically, in the case where the bent pixel electrode 109 has a widthwhich is uniform in its longitudinal direction as shown in FIG. 2, eachof the counter electrodes 104A positioned on the opposite sides of thepixel electrode 109 is formed to extend in parallel with an adjacent oneof the drain signal lines 103 on its side which faces the adjacent drainsignal line 103, and in parallel with the pixel electrode 109 on itsside which faces the pixel electrode 109.

Owing to this construction, the directions of electric fields E to begenerated between the pixel electrode 109 and the counter electrodes104A become (−).theta. with respect to the counter voltage signal line104 in the pixel area on the bottom side of FIG. 2 and (+).theta. withrespect to the counter voltage signal line 104 in the pixel area on thetop side of FIG. 2.

The reason why the directions of the electric fields E are madedifferent in this manner within one pixel area (such directions need notnecessarily be made different within one pixel area, and may also bemade different between one pixel area and another pixel area) is thatthe optical transmissivity of the liquid crystal can be varied byrotating part of its liquid crystal molecules in one direction and theother in the opposite direction with respect to a constant initialalignment direction.

By adopting this construction, it is possible to solve a problem due tothe viewing-angle dependence of the liquid crystal display panel, i.e.,the problem that the reversal phenomenon of luminance is caused when auser turns his eyes on the liquid crystal panel from an obliquedirection with respect to the main viewing angle direction thereof.

Incidentally, in this embodiment, an initial alignment direction R ofliquid crystal molecules is made approximately coincident with theextension direction of the drain signal line 103, and the rubbingdirection (initial alignment direction) of an alignment film which willbe described later is made to be a direction along the drain signal line103.

For this reason, the above-described electric field directions .theta.are set to appropriate values in relation to the initial alignmentdirection R. In general, the electric field directions .theta. are setso that the absolute value of the angle of each of the electric fields Ewith respect to the gate signal line 102 becomes smaller than theabsolute value of the angle of the same electric field E with respect tothe drain signal line 103.

The portion of the pixel electrode 109 that is superposed on the countervoltage signal line 104 is formed to have a large area, and thecapacitance element Cadd is formed between that portion and the countervoltage signal line 104. In this case, the insulating film 105 is usedas a dielectric film.

This capacitance element Cstg is formed for the purpose of, for example,enabling a video signal supplied to the pixel electrode 109 to be storedtherein for a comparatively long period. Specifically, when a scanningsignal is supplied to the thin film transistor TFT from the gate signalline 102, the thin film transistor TFT is turned on and a video signalfrom the drain signal line 103 is supplied to the pixel electrode 109via the thin film transistor TFT. After that, even in the case where thethin film transistor TFT is turned off, the video signal supplied to thepixel electrode 109 is stored therein by the capacitance element Cadd.

A protective film 108 (refer to FIG. 3) made of, for example, a siliconnitride film is formed on the entire surface of the TFT substrate 100Aformed in this manner, whereby, for example, the thin film transistorTFT can be prevented from being brought into contact with the liquidcrystal.

Furthermore, an alignment film 111 (refer to FIG. 3) which determinesthe initial alignment direction of the liquid crystal is formed on thetop surface of the protective film 108. This alignment film 111 isformed by depositing, for example, a synthetic resin film on theprotective film 108 and effecting rubbing treatment on the surface ofthe synthetic resin film in the extension direction of the drain signalline 103 as described previously.

A color filter substrate 100B is disposed in opposition to the TFTsubstrate 100A constructed in this manner, with a liquid crystal layer 9interposed therebetween. As described previously, the color filtersubstrate 100B has a construction in which the black mask 3 whichseparates the individual pixel areas is formed on theliquid-crystal-side surface of the transparent substrate 5 and the colorfilters 2 for predetermined colors are formed in the respectiveapertures of the black mask 3. Incidentally, in FIG. 2, sign BM denotesan outline which corresponds to one of the apertures of the black mask3.

FIG. 3 is a cross-sectional view showing a case where the spacer 1 isprovided at a location indicated at A in FIG. 2. FIG. 3 is also across-sectional view taken along line II-II of FIG. 2. The spacer 1shown in FIG. 3 is provided between the black mask 3 of the color filtersubstrate 100B and the drain signal line 103 of the TFT substrate 100A.The spacer 1 formed on the color filter substrate 100B is in contactwith the TFT substrate 100A, but the depression 6 is formed on thesurface of the spacer 1 that is brought into contact with the TFTsubstrate 100A.

In general, the liquid crystal panel is manufactured by stickingtogether two substrates, i.e., the TFT substrate 100A and the colorfilter substrate 100B. In the process of manufacturing the liquidcrystal panel, the TFT substrate 100A and the color filter substrate100B are disposed to oppose each other with a gap in which to interposethe liquid crystal layer 9 being provided therebetween. The spacer 1forms the gap in which to seal the liquid crystal, and is providedbetween the TFT substrate 100A and the color filter substrate 100B tokeep constant the layer thickness of the liquid crystal layer 9. Asealing material for adhesion is applied to the peripheral portion ofeach of the TFT substrate 100A and the color filter substrate 100B thatare disposed in opposition to each other, and then, the TFT substrate100A and the color filter substrate 100B are stuck together by pressure.In this pressure-sticking step, the spacer 1 is pressed against the TFTsubstrate 100A.

As shown in FIG. 3, the depression 6 is formed in the spacer 1, wherebywhen the liquid crystal panel is assembled with the TFT substrate 100Abeing stuck to the color filter substrate 100B by pressure, a portionwhich is in contact with the TFT substrate 100A and a portion which isnot in contact with the TFT substrate 100A are produced on the spacer 1.In this manner, the portion which is in contact with the TFT substrate100A and the portion which is not in contact with the TFT substrate 100Aand has the liquid crystal layer 9 between itself and the TFT substrate100A are provided on the surface of the spacer 1 that is opposed to theTFT substrate 100A, whereby it is not merely possible to obtain theportion which is in contact with the TFT substrate 100A in order toretain a normal substrate gap, but when a temporarily large load isexternally applied perpendicularly to the substrate surfaces, it ispossible to dispersively bear such load. In addition, since the area ofthe spacer 1 that is in contact with the TFT substrate 100A isordinarily small, the spacer 1 is also effective on the problem that inthe case where an external force parallel to the substrate surface isapplied to the spacer 1, even if the spacer 1 is released from theexternal force, the spacer 1 cannot be restored from its displacement,owing to friction.

A position where the spacer 1 is formed and an alignment defect due tothe spacer 1 will be described below. The spacer 1 shown in FIG. 3 isformed at the portion indicated at A in FIG. 2, and the portionindicated at A is positioned between the drain signal line 103 and theblack mask 3 and is effective in making inconspicuous an alignmentdefect caused by the spacer 1. In other words, since the drain signalline 103 is approximately parallel to the initial alignment directionindicated by an arrow R in FIG. 2, the alignment defect caused by thespacer 1 during rubbing treatment can be hidden by the black mask 3.

The alignment defect caused by the spacer 1 will be described below withreference to FIG. 4. As shown in FIG. 4, rubbing treatment is in generalperformed by bringing a roller 300 into contact with an alignment film 8while rotating the roller 300, and rubbing the alignment film 8 with theroller 300. During this time, since the spacer 1 projects from the colorfilter substrate, the roller 300 floats upward from the alignment film8, so that a portion 8A where sufficient alignment cannot be effectedoccurs at the back side of the spacer 1. In this portion 8A wheresufficient alignment cannot be effected, there occurs a display which isnonuniform with respect to that in the other portion, so that displayirregularity occurs.

However, in the case where the spacer 1 is provided on the drain signalline 103 which is approximately parallel to the initial alignmentdirection, the roller 300 moves approximately in parallel with the drainsignal line 103, so that the portion 8A where sufficient alignmentcannot be effected occurs between the drain signal line 103 and theblack mask 3. Therefore, display irregularity due to the portion 8Awhere sufficient alignment cannot be effected can be hidden by the blackmask 3.

FIG. 5 is a cross-sectional view showing a case where the spacer 1 isprovided at a location indicated at B in FIG. 2. FIG. 5 is also across-sectional view taken along line III-III of FIG. 2. In FIG. 5, thespacer 1 is provided between the black mask 3 of the color filtersubstrate 100B and the intersection of the drain signal line 103 and thecounter voltage signal line 104 on the TFT substrate 100A.

As shown in FIG. 5, a step is formed at the intersection of the drainsignal line 103 and the counter voltage signal line 104. By utilizingthis step, even if the top surface of the spacer 1 is flat, it ispossible to realize a construction in which when a large load isapplied, the step of the substrate 104A can be utilized to increase thearea of the portion of the spacer 1 that is in contact with thesubstrate 104A, thereby dispersing the large load. In other words, in anordinary case, part of one spacer is in contact with the substrate toretain the gap between the substrates, but in the case where the spacerreceives a large load, the spacer undergoes elastic deformation and theportion of the spacer that is out of contact with the substrate 104Abecause of the presence of such step also comes into contact with thesubstrate 104A and bears the large load.

In the case where steps present on a substrate are utilized, locationswhere spacers are to be disposed can be selected from among locationswhere the steps are originally present on the substrate, for example,locations on a TFT substrate where interconnection lines overlap oneanother, or locations on a color filter substrate where a color patternoverlaps a black mask pattern.

FIGS. 6A and 6B are cross-sectional views showing a case where a spaceris provided at a location indicated at D or E in FIG. 7. FIGS. 6A and 6Bare cross-sectional views taken along line IV-IV of FIG. 7. FIG. 6Ashows a case where a spacer 1 b is provided at the location indicated atD in FIG. 7, while FIG. 6B shows a case where a spacer 1 c is providedat the location indicated at E in FIG. 7. In FIG. 6A, the spacer 1 b isprovided between the black mask 3 of the color filter substrate 100B andthe intersection of the drain signal line 103 and the counter voltagesignal line 104 on the TFT substrate 100A. Since the spacer 1 b shown inFIG. 6A is provided at the intersection of the drain signal line 103 andthe counter voltage signal line 104, the spacer 1 b is provided at aposition which is increased in thickness by the thickness of the countervoltage signal line 104. In the case shown in FIG. 6B, a spacer 1 c isprovided over the drain signal line 103, and since the spacer 1 c hasapproximately the same height as the spacer 1 b provided in theconstruction shown in FIG. 6A, a gap which is approximately equal to thethickness of the counter voltage signal line 104 occurs between thespacer 1 c and the TFT substrate 100A unlike the construction shown inFIG. 6A, and a liquid crystal is present in the gap. In other words, thespacer 1 b formed at the position shown in FIG. 6A is ordinarily placedin contact with the TFT substrate 100A, and works to form and maintainthe gap between the TFT substrate 100A and the color filter substrate100B. The spacer 1 c formed at the position shown in FIG. 6B ordinarilyis not in contact with the TFT substrate 100A, but if a forceperpendicular to both substrates is applied from the outside, the spacer1 b shown in FIG. 6A is pressed and elastically deformed, so that thegap between the TFT substrate 100A and the color filter substrate 100Bbecomes narrow and the spacer 1 c also comes into contact with the TFTsubstrate 100A and bears the load. Within one liquid crystal panel, byselecting positions where to form such spacers, it is possible toappropriately adjust the number of spacers 1 b and spacers 1 c, wherebyit is possible to realize a liquid crystal display device which can copewith perpendicular or horizontal external forces relative to its liquidcrystal panel without any problem.

FIG. 8 shows a case where a step for the spacer 1 is provided on thecolor filter substrate 100B. As shown in FIG. 8, a base pattern 11 isformed under the spacer 1 at the same time that the black mask 3 or thecolor filter pattern 2 is formed. In the case shown in FIG. 8, the basepattern 11 is formed at the same time as the formation of the colorfilter 2. However, since the protective film (leveling film) 4 is formedto overlie the base pattern 11, the resultant step becomes small owingto its leveling effect. Accordingly, the size of the step is adjusted bychanging the size and shape of the base pattern 11.

As shown in FIG. 8, since the spacer 1 b is provided over the basepattern 11, the spacer 1 b is provided at a position which is increasedin thickness by the thickness of the base pattern 11. On the other hand,the spacer 1 c is provided over the black mask 3 on which the basepattern 11 is not provided. The spacer 1 c is formed by patterning aresin layer which has approximately the same film thickness as thespacer 1 b, and in the case where the liquid crystal panel is assembled,a gap occurs between the top surface of the spacer 1 c and the opposedcolor filter substrate (not shown) and the liquid crystal is present inthe gap. Specifically, the spacer 1 b is ordinarily placed in contactwith the TFT substrate, and works to form and maintain the gap betweenthe TFT substrate and the color filter substrate 100B. On the otherhand, the spacer 1 c ordinarily is not in contact with the TFTsubstrate, but if a force perpendicular to both substrates is appliedfrom the outside, the spacer 1 b is pressed and elastically deformed, sothat the gap between the TFT substrate and the color filter substrate100B becomes narrow and the spacer 1 c also comes into contact with theTFT substrate and bears the load. Within one liquid crystal panel, byselecting positions where to form such base patterns 11, it is possibleto appropriately adjust the number of spacers 1 b and spacers 1 c.

FIGS. 9A to 9D show a process diagram for forming the base pattern 11.In the step shown in FIG. 9A, a metal film (a two-layer film made ofchromium Cr and chromium oxide) is formed on a transparent substrate bya sputtering method or the like, and is then patterned into a desiredshape by using a photolithographic method, thereby forming the blackmask 3. Incidentally, a resin film may also be substituted for such ametal film.

Then, in the step shown in FIG. 9B, a resist material 12 which is mixedwith a pigment to absorb light of particular wavelength is dropped ontothe substrate on which the black mask 3 has been formed. The resistmaterial 12 is applied so that a uniform film thickness is obtained, andis dried. In the step shown in FIG. 9C, the dried resist material 12 ispatterned by using a photolithographic method or the like, therebyforming the color filter 2. At the same time, the base pattern 11 isalso formed by patterning. Then, in the step shown in FIG. 9D, theprotective film 4 is formed to cover the color filter 2 and the basepattern 11.

During the patterning of the base pattern 11 by the use of a photomask,if the shape of the base pattern 11 is small, the amount of exposuredecreases owing to diffraction of light, depending on the distancebetween the photomask and the substrate. Since a negative type of resistmaterial is used, if the amount of exposure is small, the resistmaterial becomes easy to remove and the height of the base pattern 11can be decreased. For this reason, by changing the shape of the basepattern 11, it is possible to adjust the height of the base pattern 11.

FIGS. 10A to 10C show a process diagram for forming the spacers 1. Inthe step shown in FIG. 10A, first, a substrate on which the protectivefilm 4 (leveling film) is formed on the black mask 3 and the colorfilter 2 is prepared. Then, precleaning and drying are performed on thesubstrate on which the protective film 4 is formed, and subsequently, anaqueous solution type of resist material 13 is dropped onto and appliedto the substrate. The resist material 13 is dried and formed into afilm. Then, in the step shown in FIG. 10B, a photomask 14 is arranged inposition and light 16 is irradiated onto portions 15 in each of which toform the spacer 1, thereby effecting exposure. At this time, portions 17each having an insufficient amount of exposure are formed as shown inFIG. 10B owing to diffraction of light as the result of the relationshipbetween the shape of the photomask 14 and the distance between thephotomask 14 and the resist material 13. Then, as shown in FIG. 10C, theunexposed portion of the resist material 13 is removed with a remover.In the portions 15 which are sufficiently exposed by the use of thephotomask 14, the polymerization reaction of a resin which constitutesthe resist material 13 proceeds and its molecular weight increases, sothat the portions 15 become difficult to solve with the remover, ascompared with a portion which is not irradiated with the light 16. Onthe other hand, the portions 17 having an insufficient amount of lightbecome slightly easy to solve with the remover, as compared with theportions 15 which are sufficiently exposed. For this reason, when theresist material 13 is immersed to remove the unexposed portion of theresist material 13, the resin of the portions 17 each having aninsufficient amount of exposure is solved by a small amount.Accordingly, the depressions 6 are respectively formed on the topportions of the spacers 1.

FIGS. 11A to 11C show a process diagram for forming the spacers 1 eachhaving the depression 6 by changing the amount of exposure by using twokinds of photomasks. In the step shown in FIG. 11A, first, the aqueoussolution type of resist material 13 is applied to a substrate on whichthe black mask 3, the color filter 2 and the protective film 4 areformed. Then, a photomask 14 a is arranged in position and the light 16is irradiated onto the portions 15 in each of which to form the spacer1, thereby effecting exposure. After that, in the step shown in FIG.11B, a photomask 14 b is used to irradiate the light 16, but during thistime, portions 17 which are not sufficiently exposed are formedaccording to the difference in shape between the photomasks 14 a and 14b. After that, the unexposed portion of the resist material 13 isremoved with a remover, whereby the spacers 1 are formed. As shown inFIG. 11C, since the portions 17 which are not sufficiently exposed aresolved with a small amount of remover, the depressions 6 (steps) arerespectively formed on the spacers 1.

The case in which the spacers 1 are provided in a so-called verticalelectric field type of liquid crystal display device will be describedbelow with reference to FIG. 12. In the vertical electric field type ofliquid crystal display device, an electric field is applied to a liquidcrystal layer provided between an electrode formed on one of two opposedsubstrates and an electrode formed on the other, thereby changing thealignment direction of the liquid crystal layer. FIG. 12 is a viewshowing the construction of one pixel area of the so-called verticalelectric field type of liquid crystal display device, and is a plan viewshowing the liquid-crystal-side surface of the TFT substrate 100A whichis disposed in opposition to the color filter substrate 100B with theliquid crystal interposed therebetween.

Within a liquid crystal panel, individual pixels are disposed in matrixform to constitute a display part. Although FIG. 12 shows one pixel forthe sake of simplicity in illustration, adjacent pixels exist,respectively, on the right, left, top and bottom side of the one pixelshown in FIG. 2, and the construction of each of the adjacent pixels isthe same as that of the one pixel shown in FIG. 12.

As shown in FIG. 12, the gate signal lines 102 which are extended in thehorizontal (x) direction and are juxtaposed in the vertical (y)direction are formed on the surface of the TFT substrate 100A. Thesegate signal lines 102 are made of a material such as chromium (Cr).

Each adjacent one of the gate signal lines 102, together with eachadjacent one of the drain signal lines 103 to be described later (whichare extended in the vertical (y) direction and are juxtaposed in thehorizontal (x) direction in FIG. 12), is formed to surround arectangular area, and the rectangular area constitutes one pixel area.

Light shield films 114 which are disposed in parallel with andadjacently to the respective drain signal lines DL are formed in thepixel area, and these light shield films 114 are formed at the same timethat, for example, the gate signal lines 102 are formed.

These light shield films 114, together with the black mask 3 formed on acolor filter substrate (not shown), have the function of separatingsubstantial pixel areas, and since the light shield films 114 are formedon the TFT substrate 100A on which the pixel electrode 109 which will bedescribed later is formed, the light shield films 114 can be formedwithout the risk of positional deviation.

The insulating film 105 (refer to FIG. 13) which is made of, forexample, SiN is formed on the entire surface of the TFT substrate 100Aon which the gate signal lines 102 and the light shield films 114 areformed in the above-described manner.

This insulating film 105 has the function of an interlayer insulatingfilm between the gate signal lines 102 and the drain signal lines 103which will be described later, the function of gate insulating films forthe thin film transistors TFT (which will be described later) in areasin which the respective thin film transistors TFT are formed, and thefunction of dielectric films for the additional capacitances Cadd (whichwill be described later) in areas in which the respective addedcapacitances Cadd are formed

Each of the thin film transistors TFT is formed to be superposed on thegate signal line 102 at the bottom left of the pixel area as viewed inFIG. 12, and in this area, the semiconductor layer 106 which is formedof, for example, a-Si (amorphous silicon) is formed on the insulatingfilm 105.

The drain electrode 103A and a source electrode 107A are formed on thesurface of the semiconductor layer 106, thereby forming a thin filmtransistor having a reversed-staggered structure which has a gateelectrode made of a part of the gate signal line 102 and a gateinsulating film made of a part of the insulating film 105.

The drain signal line 103 is formed of, for example, chromium (Cr), andplural drain signal lines 103 are formed to be extended in the vertical(y) direction and to be juxtaposed in the horizontal (x) direction.

A portion of the drain signal line 103 is extended to the surface of thesemiconductor layer 106 in an area in which the thin film transistor TFTis formed, whereby the drain electrode 103A of the thin film transistorTFT is formed.

The source electrode 107A of the thin film transistor TFT which isdisposed in opposition to the drain electrode 103A is formed at the sametime that the drain signal line 103 is formed.

A protective film 108 (refer to FIG. 13) which is made of, for example,SiN is formed on the entire surface of the TFT substrate 100A on whichthe required electrodes are formed, and a contact hole 108A is formed inthe protective film 108 over the central portion of an extended portionof the source electrode 107A.

Furthermore, the transparent pixel electrode 109 which is made of, forexample, ITO (Indium-Tin-Oxide) is formed on the top surface of theprotective film 108. As shown in FIG. 12, this pixel electrode 109 isformed in an area surrounded by adjacent ones of the gate signal lines102 and adjacent ones of the drain signal lines 103.

In this case, at the time of formation of the pixel electrode 109, thepixel electrode 109 can be connected to the source electrode 107Athrough the contact hole 108A.

One of the adjacent gate signal lines 102 underlies the thin filmtransistor TFT through which to supply a video signal to the pixelelectrode 109, and one side of the pixel electrode 109 is formed to besuperposed on part of the other of the adjacent gate signal lines 102along its entire length, thereby constituting the capacitance elementCadd.

The capacitance element Cadd uses as its dielectric film the insulatingfilm 105 and the protective film 108 that are provided between the gatesignal line 102 and the pixel electrode 109, and the capacitance valueis related to the area of superposition of the pixel electrode 109 onthe gate signal line 102.

This capacitance element Cadd has a function such as causing a videosignal to be stored in the pixel electrode 109 for a comparatively longperiod after the thin film transistor TFT is turned off.

The alignment film 111 (refer to FIG. 13) which abuts on the liquidcrystal is formed on the entire surface of the TFT substrate 100A onwhich the pixel electrodes 109 are formed in the above-described manner,so that the initial alignment direction of the liquid crystal isdetermined by the alignment film 111.

The color filter substrate 100B is disposed in opposition to the TFTsubstrate 100A which is constructed in this manner, with the liquidcrystal being interposed therebetween.

FIG. 13 is a cross-sectional view taken along line V-V of FIG. 12, andshows the spacer 1 provided at a position indicated at F in FIG. 12.FIG. 13 shows the color filter substrate 100B as well as the TFTsubstrate 100A, and is a cross-sectional view showing the state in whichthe TFT substrate 100A and the color filter substrate 100B areassembled.

As shown in FIG. 13, the black mask 3 which separates the individualpixel areas is formed on the liquid-crystal-side surface of the colorfilter substrate 100B, and the color filters 2 for predetermined colorsare formed in the respective apertures of the black mask 3. Theprotective film (leveling film) 4 is formed to cover the black mask 3and the color filters 2. A common electrode 7 which is common to theindividual pixel areas and is made of, for example, ITO is formed on theentire surface of the protective film 4. The spacer 1 is formed on thecommon electrode 7. In addition, the alignment film 8 which abuts on theliquid crystal is formed on the entire surface of the common electrode 7on which the spacer 1 is provided.

A position at which the spacer 1 is formed is intermediate between theblack mask 3 and the gate signal line 102. Since the gate signal line102 has a wide line width compared to the drain signal line 103, thepositioning of the spacer 1 that is required to dispose the spacer 1 ata flat position is easy compared to the case of disposing the spacer 1on the drain signal line 103.

FIG. 14 shows the position of the spacer 1 on the color filter substrate100B in the case where the spacer 1 is provided at the positionindicated at F in FIG. 12. The spacer 1 is provided on the black mask 3and is hidden so as not to stand out during the observation of theliquid crystal display device. In addition, in the vertical electricfield type of liquid crystal display device, its initial alignmentdirection is an oblique direction with respect to the drain signal line103 as shown by an arrow G in FIG. 14, so that alignment defect due tothe spacer 1 is difficult to hide on the drain signal line 103. For thisreason, the spacer 1 is provided near the intersection of the drainsignal line 103 and the gate signal line 102, and is provided at aposition where the area of the black mask 3 can be utilized as an areawhich is wide in the oblique direction.

The equivalent circuit and its peripheral circuit of a display partwhich includes the pixels of the liquid crystal display device will bedescribed below with reference to FIG. 15. FIG. 15 is a circuit diagramwhich is drawn to correspond to an actual geometric arrangement. Sign ARdenotes a matrix array in which plural pixels are arrayedtwo-dimensionally.

In FIG. 15, sign “X” means any one of the video signal lines 103, andsuffixes “G”, “B” and “R” are added to the sign “X” to correspond togreen, blue and red pixels, respectively. Sign “Y” means any one of thegate signal lines 102, and suffixes “1”, “2”, “3”, . . . , and “end” areadded to the sign “Y” in accordance with the sequence of scanningtiming.

The gate signal lines Y (whose suffixes are omitted) are connected to avertical scanning circuit V, and the drain signal lines X (whosesuffixes are omitted) are connected to a video signal driver circuit H.A circuit SUP includes a power source circuit for obtaining a pluralityof divided stabilized voltage sources from one voltage source, and acircuit for exchanging information for a CRT (cold cathode ray tube)received from a host (a host computer) into information for the liquidcrystal display device.

The construction of constituent parts of the liquid crystal displaydevice will be described below with reference to FIG. 16. FIG. 16 is anexploded perspective view illustrating individual constituent parts ofthe liquid crystal display device. Sign SHD denotes a frame-shapedshield case (a metal frame) made from a metal plate, sign LCW denotes adisplay window, sign PNL denotes a liquid crystal panel, sign SPBdenotes an optical diffusion sheet, sign LCB denotes a light guide, signRM denotes a reflecting sheet, sign BL denotes a backlight fluorescenttube, and sign LCA denotes a backlight case. The liquid crystal displaydevice is assembled by stacking these members in the shown layeredarrangement.

The liquid crystal display device is secured as a whole by hooks andclaws provided on the shield case SHD. The backlight case LCA has ashape which accommodates the backlight fluorescent tube BL, the opticaldiffusion sheet SPB, the light guide LCB and the reflecting sheet RM,and converts the light of the backlight fluorescent tube BL arranged ona side of the light guide LCB into backlight which becomes uniform on adisplay screen, by means of the light guide LCB, the reflecting sheet RMand the optical diffusion sheet SPB, and emits the backlight to theliquid crystal display panel PNL. An inverter circuit board PCB3 isconnected to the backlight fluorescent tube BL and serves as the powersource of the backlight fluorescent tube BL.

In the invention, as described hereinabove, spacers which dispersivelybear a temporarily large load only when it is applied are disposed inaddition to spacers which retain the gap between substrates ordinarily,only the necessary minimum number of spacers function, but when a largeload is temporarily applied from the outside, auxiliary spacersdispersively bear the load, whereby it is possible to achieve theadvantage of preventing irreversible deformation of the spacers.

While we have shown and described several embodiments in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible of numerous changes and modifications asknown to those skilled in the art, and we therefore do not wish to belimited to the details shown and described herein but intend to coverall such changes and modifications as are encompassed by the scope ofthe appended claims.

1. A liquid crystal display device comprising: a first substrateincluding color filters; a liquid crystal layer; a second substratedisposed opposite to the first substrate across the liquid crystallayer; a plurality of first signal lines formed above the secondsubstrate, a plurality of second signal lines intersecting the firstsignal lines over an insulating film therebetween; a plurality of pixelregions each formed as being surrounded by respective neighboring firstsignal lines and second signal lines, and having a pixel electrode; abase pattern formed between pixel electrodes of neighboring pixelregions; a plurality of first spacers each formed above a main surfaceof the first substrate and arranged above a first portion thereofbetween said pixel electrodes of neighboring pixel regions andoverlapping with the base pattern in a plan view; and a plurality ofsecond spacers each formed above the main surface of the first substrateand arranged above a second portion thereof between said pixelelectrodes of neighboring pixel regions and not overlapping with thebase pattern in a plan view, wherein when the first substrate is notsubjected to an external force and not elastically deformed, each of thesecond spacers is spaced from a stacked structure formed on the secondsubstrate to accommodate portions of the liquid crystal layertherebetween, and each of the first spacers formed above the basepattern contacts directly with the stacked structure formed on thesecond substrate, said first portion includes the base pattern, saidsecond portion does not include the base pattern, and said first portionis disposed apart from said second portion across the pixel region, andeach of the first spacers and the second spacers has a depression.
 2. Aliquid crystal display device, according to claim 1, wherein each of thesecond spacers contacts with the uppermost of said second portion of thestacked structure formed on the second substrate, when the firstsubstrate is subjected to an external force and elastically deformed. 3.A liquid crystal display device, according to claim 1, wherein the basepattern is covered by a protective film formed between the base patternand the first spacers.